富氏谱分析法模拟地壳垂直运动的地学依据及其策应力模型     

张勤  范一中 《大地测量与地球动力学》2001,21(4):76-80

应用地壳波浪与镶嵌构造学说对富氏谱分析法提取地壳垂直形变信息的科学性做了地质学意义上的阐释 ,并提出了根据多期形变资料提取特定波段上构造策应力的数学模型  相似文献   

The dry dredgers of Cincinnati, Ohio, USA     

President  JACK W. KALLMEYER & Professor of Geology  DAVID L. MEYER 《Geology Today》1997,13(6):228-230

  相似文献   

NORTHERN AND SOUTHERN HEMISPHERIC POLAR LOWS——A COMPARATIVE STUDY          下载免费PDF全文

Erik A.Rasmussen 《Acta Meteorologica Sinica》1993,(3)

Northern Hemispheric“polar lows”,i.e.maritime,small,but fairly intense cyclonic systems have been studied formore than two decades.Recently researchers have turned their attention towards the occurrence of polar lows and othersmall-scale cyclonic disturbances on the Southern Hemisphere.In this paper a short account of our present knowledgeof Northern Hemispheric polar lows will be given,followed by some preliminary results of an investigation of the natureand occurrence of polar lows on the Southern Hemisphere.  相似文献   

K-H Instability of Dust Plasma     

Shi Zhi-dong  Li Zhong-yuanUniversity of Science  Technology of China  Hefei    PRC Advanced Centre for Earth Science  Astronomy  Third World Academy of Science 《紫金山天文台台刊》1996,(2)

Areview about K-H instability related to comet tail is presented.The effect of dust graing on KHI is theoretically analysed and relations of critical shear to excit KHI with the properties of dust grains both for sheared ion flow and for sheared dust flow re put out.Their possible application in comet tail is suggested.  相似文献   

PROPAGATION OF 30—60 DAY LOW FREQUENCY OSCILLATIONS AND THEIR INFLUENCE UPON THE SUBTROPICAL WESTERLIES JET STREAM DURING NORTHERN HEMISPHERE WINTER          下载免费PDF全文

史玉光  李清泉 《Acta Meteorologica Sinica》1996,(2)

Based on daily ECMWF gridpoint data of two winters during 1981—1983 including an ENSOyear,propagation of low frequency oscillations(LFO)during Northern Hemisphere winters andtheir influences upon 30—60 day oscillations of the subtropical jet stream are studied with the sta-tistical methods as complex empirical orthogonal function(CEOF)and so on.Results show that inthe winter of a normal year(1981—1982),30—60 day oscillations in the subtropical zone aremainly in the northern and southern flanks of exit region of jet stream.In the ENSO year(1982—1983),they are mainly in the vicinity of entrance and exit regions of jet stream.Intraseasonalchanges of subtropical jet stream manifested themselves as latitudinal fluctuation or longitudinalprogression or regression of about 40 day period.There are marked differences between propagat-ing passages of low frequency modes responsible for changes of subtropical jet stream in the normalyear(1981—1982)and in the ENSO year(1982—1983).Changes of oscillation amplitude showobvious phases.In general,the one in late winter is stronger than that in early winter,strongestone occurs in February.  相似文献   

Early warning research on salt-alkalization desertification in western Songnen Plain     

BIAN Jian-min  LIN Nian-feng  TANG Jie College of Environment  Resources  Jilin  University  Changchun  Jilin  China 《东北亚地学研究》2005,(Z1)

Desertification is an environmental issue in the world. The salt-alkalization desertification land area formed by both primary and secondary salt-alkalization has extended in a large scale, which has become a significant eco-environmental problem. Based on the characteristics of eco-environment and the situation of desertification in western Songnen plain, this paper reports the analyzes of its formation in background and cause. An early warning system on the salt-alkalization desertification is established and the GIS technology is used to abstract the information of desertification evaluation index. Supported by the integrated technology of the GIS and ANN, the orientation and quantitative result of desertification are gained, which is helpful to the eco-environment protection and resource development in western Songnen Plain.  相似文献   

巴颜喀拉山东段及其邻区大地电磁测深成果地质解释     

庞存廉  方胜  夏元祁 《青海国土经略》1996,(1)

本文主要依据青海省囊歉至大河坝大地电磁测深成果,并结合重力资料对巴颜喀拉及南北两侧地区的壳幔结构进行了地质解释。指出了该区壳幔存在4个明显的低阻层,并简述了它们的形态特征,推断了其地质含意。认为昆中断裂带与昆南断裂带间是一个巨大的构造混杂岩带,影响深度亦很大。推断该区可能存在太古代地层。划出了8条壳幔断裂带,认为昆中断裂应是塔里木—华北板块与华南板块的分界线。  相似文献   

Study on numerical simulation to water lowering in an open coal mine digging     

Yanjun ZHANG Fenglong ZHANG Full QI Fuquan NI 《东北亚地学研究》2006,9(2):199-203

In view of the situation of excavation of open coal mine for the underground water disaster,we should carry out simulation studies for the numerical value of the water lowering project and improve the accuracy and the level of the water lowering project.On the basis of the hydrological geological conditions of certain open mine digging,a more reasonable seepage numerical model was built according to MODFLOW.It was simulated in advance that the process of the confined water level descending with the time,and combining with the actual observations to test the correctness of the model.The calculation showed that the results coincided well with the results of actual measurement.Based on this,different water lowering numerical simulations were built for the open coal mine digging.It could be simulated and forecast that the changes of the groundwater level in drainage process within and outside the mine pit,and it was quantitatively assessed that the possible water lowering result of the opencast water drainage process,which provide an important basis for the actual water lowering project and the possible project disposal.  相似文献   

1989年8月17日太阳射电尖峰事件的准周期脉动及EFB分析     

张衡  孔勇进  龚元芳  楼恩蕊  尚琼珍 《中国天文和天体物理学报》1994,(1)

本文分析了云南天文台１０ｍ射电望远镜在２ｌｃｍ波段上观测到的一次尖峰辐射事件，这次事件发生在５６２９活动区（Ｓ１６Ｗ１０９），它伴随了Ｘ２·９／ＳＦ耀斑及边缘耀斑环，并且有质子流量的上升和一次罕见的地磁场突然反相脉冲与之对应．我们从耀斑环的Ｈβ照片可以看出，在尖峰辐射发生前，原先存在的耀斑环的顶部开始变亮，而尖峰开始后环顶亮度达到极大，说明这次尖峰辐射与耀斑环顶部增亮有关，辐射很可能来自环顶．从尖峰事件的时间轮廓得到的ＦＦＴ功率谱表明存在１５０ｍｓ的准周期脉动．按照Ｍｃｌｅａｎ等人的模型，即脉动是由俘获在磁通管内的电子的径向振荡引起，可以推断，这次尖峰辐射与Ｆｅｒｍｉ机制激发快速电子有关，且尖峰的发生需要被俘获的电子．此外，我们将这次尖峰事件分解为几百个元耀斑爆发（ＥＦＢ），并且讨论了这些ＥＦＢ的性质．  相似文献   

Molecular phylogenetic analysis of attached Ulvaceae species and free-floating Enteromorpha from Qingdao coasts in 2007   总被引：3，自引：1，他引：2  

姜鹏  王金锋  崔玉琳  李友训  林瀚智  秦松 《中国海洋湖沼学报》2008,26(3)

Based on the sequence data of the nuclear ribosomal DNA internal transcribed spacer(ITS) 1,5.8 S,and ITS 2,the molecular phylogeny was analyzed on Ulvaceae species collected from Qingdao coasts in summer of 2007,including 15 attached Ulva and Enteromorpha samples from 10 locations and 10 free-floating Enteromorpha samples from seven locations.The result supported the monophyly of all free-floating Enteromorpha samples,implying the unialgal composition of the free-floating Enteromorpha,and the attached Ulvaceae species from Qingdao coasts were grouped into other five clades,suggesting that they were not the biogeographic origin of the free-floating Enteromorpha in that season.  相似文献